I don't think they are. There is just a white space where they should be. To add them, I clicked on the YouTube button in the editor and copy pasted my YouTube URL.
Do you put in the entire YouTube URL or just a portion of it?
When they weren't showing properly, I just made a link. I thought maybe it doesn't work on SEOClerks. Then I noticed other listings have videos right in the description. I must be doing something wrong. Can anyone please help?